Question

Dada a função f(x) X² -5x + 6 x para f(x)=20

Answer 1

f(x) = x² - 5x + 6
f(x) = 20  
Assim, x² - 5x + 6 = 20
x² - 5x + 6 – 20 = 0
x² - 5x – 14 =0
 
 Delta  = (-5)² - 4*1*(-14)
           = 25 + 56     
            = 81  
X = - (-5) +-  √ 81              
             2*1
x’ = 5 + 9   = 7        
        2   

x’’ = 5 – 9  = -2       
         2

Answer 2

$f(x)=x^{2}-5x+6 \\ \\ f(x)=20 \\ \\ 20=x^{2}-5x+6 \\ x^{2}-5x+6-20=0 \\ x^{2}-5x-14=0 \\ \\ \Delta=(-5)^{2}-4.1.(-14) \\ \Delta=25+56 \\ \Delta=81 \\ \\ x'= \frac{-(-5)+ \sqrt{81}}{2.1} \\ x'= \frac{5+9}{2} \\ x'= \frac{14}{2} \\ \boxed {x'=7} \\ \\ x''= \frac{-(-5)- \sqrt{81}}{2.1} \\ x''= \frac{5-9}{2} \\ x''= \frac{-4}{2} \\ \boxed {x''=-2}$